[S/M] Giga Drain on Volcarona

[P35]

Hey I need a giga drain volcarona for a special sweeper but I heard that it's impossible to get it on volcarona in s/m. I just wasted like a week breeding, ev training, level grinding, etc to get a competitive volcarona just to find out that I can't get giga drain on it afterwards . Anyway can someone can somehow get giga drain on my volcarona. If not that's a week of my life down the drain...